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Ji-Hoon Kim Jeongho Lee Tae-Jin Cheong Rak-Hyeon Kim Dong-Chan Koh Jong-Sik Ryu Ho-Wan Chang 《Journal of Hydrology》2005,300(1-4):188-198
The purpose of this study is to apply time series analysis to investigate whether the groundwater quality in the coastal area is affected by the tide. Continuous and regular in situ monitoring data of electrical conductivity (EC) and groundwater level, and tidal level data measured by the National Oceanographic Research Institute were used for the time series analysis. Through the time series analysis, it is known that EC and groundwater level conspicuously fluctuate with two periodicities (15.4 and 0.52-day), which is very similar to those of the tide. Also the behaviors of their fluctuations vary in accordance with the tidal period. These indicate that the groundwater quality has been mainly controlled by the tidal level, and the strength of tidal effect on the groundwater quality is different according to the tidal period. 相似文献
2.
Periodicites in hydrologic data are frequently estimated and studied. In some cases the periodic components are subtracted from the data to obtain the stochastic components. In other cases the physical reasons for the occurrence of these periodicities are investigated. Apart from the annual cycle in the hydrologic data, periods corresponding to the 11 year sunspot cycle, the Hale cycle and others have been detected.The conclusions from most of these studies depend on the reliability and robustness of the methods used to detect these periodicities. Several spectral analysis methods have been proposed to investigate periodicities in time series data. Several of these have been compared to each other. The methods by Siddiqui and Wang and by Damsleth and Spjotvoll, which are stepwise procedures of spectrum estimation, have not been evaluated. 相似文献
3.
W. G. Tifft 《Astrophysics and Space Science》1995,227(1-2):25-39
Redshift quantization has three main facets: 1) the internal organization of galaxies, 2) differential effects between galaxies in physical systems, 3) global effects linking all galaxies and cosmology. The subject originated as an outgrowth of redshift correlation studies including studies of internal kinematics of galaxies. While possibly central to understanding redshift quantization, this aspect is complex and largely undeveloped. The bulk of the evidence for redshift quantization comes from differential and global periodicity testing. More recently redshift variability has been associated with the phenomenon. Early work in theory led to a determination ofq0 close to 0.5. A new association between quantization and the Cosmic Background Radiation further links redshift quantization with basic cosmology. 相似文献
4.
《地学前缘(英文版)》2019,10(6):2251-2263
In the northeastern(NE) Arabian Sea,the fluctuation in terrestrial and freshwater runoff directly depends on southwest monsoon(SWM) precipitation as well as the meltwater flux provided by Indus River.Therefore,analysis of multi-proxy spectral signatures was carried out to trace the high-resolution SWM periodicities and their influence on the productivity,regional sea level fluctuations and depositional processes in the NE Arabian Sea.The time series data of stable isotopes of oxygen(δ~(18)O_(G.ruber)).carbon(δ~(13)C_(G.ruber) and δ~(13)C_(org)) and nitrogen(δ~(15)N).Total Organic Carbon(TOC),planktic-benthic foraminiferal ratio(P/B ratio) and63 μm coarse fraction(CF) were used from two coastal sedimentary cores located offshore Saurashtra,NE Arabian Sea(Core SK-240/485 having 88 m water depth;Core GC/SK-240/496 having 174 m water depth).The REDFIT based spectral analysis recorded significant periodicities(90% significance) in δ~(18)0 time series centered at~1609,~667,~525,~296,~290 and~256 years.Further,the significant periodicities recorded in carbon isotopes time series(δ~(13)C_(G.ruber) and δ~(13)C_(org))centered at~681,~512,~471,~452,~438,~360,~292,~275,~269,~245 and~209 years.The significant periodicities in TOC include~471 and-322 years whereas δ~(15)N time series recorded significant periodicity centered at-360 years.The significant periodicities in P/B ratio time series centered at~512,~388,~304,~250,~235,~217,~152,~139 and~135 years while CF recorded~268,~216,~209,~198,~188,~173 and~140 years significant periodicities.The observed periodicities in the multi-proxy record consist of similar cycles(within the radiocarbon dating error) which also natch with previously reported solar insolation influenced SWM and other global and regional cycles.Further,the stationarity of the data has been verified using wavelet analysis and shows similar periodicities as observed in REDFIT analysis.Thereafter,the depositional behaviour was studied using correlation analysis of the common periods of δ~(18)0 time series of both the cores.The result suggests that the depositional behaviour was different for both the core sites during the early Holocene and became similar during the middle Holocene.The correlation analysis of Total Solar Index(TSI) with δ~(18)O time series reveals a significant correlation with the core SK-240/485 whereas an insignificant correlation with the core GC/SK-240/496.These observations suggest that the solar insolation has been a leading factor responsible for the SWM trends during the Holocene which may have further influenced the productivity.regional sea level fluctuations and depositional conditions in the NE Arabian Sea.However,these trends are better preserved in shallow marine sediments as compared to the deeper marine sediments. 相似文献
5.
We investigate here the fluctuations in the total, open and closed solar magnetic flux (SMF) for the period 1971–1999 by means of the maximum entropy method in the frequency range 5×10−9–10−7 Hz (6 yr to 120 days). We use monthly data for the total, open and closed magnetic solar fluxes. Periodicities found in the series are similar showing that there is some relationship between the fluxes. The most important finding of this work is the existence of fluctuations at around 1.3 and 1.7 yr in the SMF with alternating importance during consecutive even and odd solar cycles. These fluctuations are directly related with variations present in cosmic rays, solar wind parameters and geomagnetic activity indexes. A quasi-triennial periodicity previously found in sunspots and other solar phenomena is also of importance. The SMF is generated by the action of the solar dynamo; therefore, it is through the magnetic flux that the solar dynamo influences several heliospheric phenomena. 相似文献
6.
A. R. Rao G. D. Jeong Fi-John Chang 《Stochastic Environmental Research and Risk Assessment (SERRA)》1992,6(4):270-288
Periodicites in hydrologic data are frequently estimated and studied. In some cases the periodic components are subtracted from the data to obtain the stochastic components. In other cases the physical reasons for the occurrence of these periodicities are investigated. Apart from the annual cycle in the hydrologic data, periods corresponding to the 11 year sunspot cycle, the Hale cycle and others have been detected.The conclusions from most of these studies depend on the reliability and robustness of the methods used to detect these periodicities. Several spectral analysis methods have been proposed to investigate periodicities in time series data. Several of these have been compared to each other. The methods by Siddiqui and Wang and by Damsleth and Spjotvoll, which are stepwise procedures of spectrum estimation, have not been evaluated.Two of the methods of spectral analysis proposed by Siddiqui and Wang and by Damsleth and Spjotvoll are investigated in this study by using generated and observed data. Siddiqui and Wang's method is found to be superior to the Damsleth and Spjotvoll's method. 相似文献
7.
R. P. Kane 《Solar physics》2007,246(2):487-493
Three series (1876 – 1986, 1886 – 1996, and 1896 – 2006) of 111 annual values of sunspot number R
z in each were subjected to spectral analysis to detect periodicities by the maximum entropy method (MEM), and the periodicities
so obtained were used in a multiple regression analysis (MRA) to estimate the amplitudes and phases. All series showed roughly
similar spectra with many periodicities (24 or more), but most of these were insignificant. The significant periodicities
(far exceeding 2σ) were near 5, 8 – 12, 18, and 37 years. Using the amplitudes and phases of these, we obtained reconstructed series, which
showed good correlations (+ 0.7 and more) with the original series. When extrapolated further in time, the reconstructed series
indicated R
z(max) in the ranges 80 – 101 (mean 92) for cycle 24 during years 2011 – 2014, 112 – 127 (mean 119) for cycle 25 during years
2022 – 2023, 115 – 120 (mean 118) for cycle 26 during years 2032 – 2034, and 100 – 113 (mean 109) for cycle 27 during 2043 – 2045. 相似文献
8.
Total ozone data series for 1957–82 at ten locations were subjected to Maximum Entropy Spectral Analysis. Besides the annual, semi-annual, and quasi-biennial oscillations, peaks were noticed at 3.5–4, 6–7, and 10–11 years. For Arosa, Switzerland, for a longer period (1932–71), an additional peak was indicated at about 16 years. 相似文献
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